This invention relates to a keyed, pin-tumbler type of lock having a special abutment portion on the associated key which normally prevents removal of the key from the lock cylinder, but a separate key removal member may be inserted adjacent the key to eliminate the effectiveness of the key special abutment portion, thereby permitting normal key removal from the lock cylinder. With this arrangement, once the key is inserted in the lock cylinder, this lock is freely operable by the key to and between its locked and unlocked conditions while the key is always positively retained in the lock cylinder. But if it is desired to remove the key in either of the locked or unlocked conditions of the lock, the key removal member may be brought into use permitting such key removal. Such a lock construction is particularly useful in a door interior lockset where the conditions dictate that, although the door is normally retained locked, it must be capable of being quickly unlocked under emergency restrictions, yet there are occasions when it is desirable to retain the door securely locked against persons not having the proper key.
In recent years, it is well known that the incidence of crime has been rapidly rising and this includes the unauthorized entry by criminals into residences for the commission of burglary, as well as serious crimes against occupants. This, of course, has resulted in well founded fears by the occupants of residences, both relative to the loss of property and in most cases more important, the risk of physical injury. The result is that most residences in these times have properly installed locks for retaining the exterior doors of the residence at all times locked, whether any of the occupants are then therein or all are absent.
Where the particular exterior door of the residence is a solid door without glass openings and the surrounding residence walls within an appropriate distance from the door are likewise solid without glass openings, convenient door security may be most easily provided. A lockset of the usual keyed lock form may be provided at the exterior of the door and a lockset of usual thumb lever operation form, not requiring a key, may be used at the interior of the door. The exterior lockset may be locked or unlocked with the key as desired, and the interior lockset may be locked or unlocked merely by hand actuation of the thumb lever, so that the interior lockset, particularly, may always be quickly unlocked by hand and without a key at any time while, at the same time, this non-key operated interior lockset is never accessible to an attempted intruder without actual solid door or wall penetration. Equally important, in the event of an emergency occurring within the residence when occupants are therein, most usually such emergency being a fire, the residence exterior doors may be quickly opened from within without a key merely by actuation of the thumb lever actuators of the interior locksets.
A completely different situation is presented, however, when the architecture of the residence is such that the particular exterior door has glass openings therein or the walls closely adjacent the particular exterior door have such glass openings therein. Since an intruder can quickly break the glass of the door or wall, non-keyed, thumb lever actuated locksets are not practical even for interior lockset use since it is easy for the intruder to break the glass, reach in and quickly unlock the door by use of the interior thumb lever actuated lockset. Although in this situation, when the occupants are within the residence, breaking glass usually will be heard and the proper police authorities or other assistance against the intruder can be quickly sought. This, however, is not true when the occupants are completely absent, in which case, the intruder is then free to burglarize the residence.
In the case where exterior doors are involved with the described glass openings, therefore, both keyed exterior and keyed interior locksets are strongly recommended if an effective frustration of the intruder is to be accomplished. Although this arrangement is perfectly satisfactory when all occupants are absent from the residence since, if the intruder breaks the glass and gains physical access to the interior lockset, he still cannot open the door without the key for the interior lockset, it still presents certain dangers during times when occupants are within the residence. Assume, for instance, that occupants are within the residence, the door interior lockset is of the key lock type and has been properly locked with the key removed, and still further assume that an emergency, such as a fire, occurs requiring quick exit from the residence by the occupants through the locked door, it can be seen that an obvious "panic" situation can be presented. To exit, the occupants must first quickly locate the key for the interior lockset, and then unlock the same, before the door can be opened and it is well known that such a "panic" situation may result in a failure to open the door and the very possible trapping of the occupants within the residence.
To avoid the possibility of such a "panic" situation arising where keyed, interior locksets are necessary, the answer is obvious, that is, when occupants are within the residence and a door lock is required to be retained locked, keep the key positioned in the lock at all times so that the lock can be quickly unlocked and the door opened in the event of an emergency situation arising. This has been strongly recommended by fire authorities. Again, even though it is possible for an intended intruder to break the glass of a glass opening, reach inside the residence and unlock the interior lockset using the key positioned therein, the sound of breaking glass will be heard by the occupants and the necessary defensive actions taken.
However, keeping a normally removable key in an interior lockset while the occupants are present within the residence, particularly in an active residence, is not necessarily a simple matter. For instance, with occupants moving frequently past the locked exterior door, there is always the possibility that the key will be inadvertently accidentally displaced from the lockset and without the key, the same "panic" situation can occur. Probably much more likely is where certain of the occupants are young children which can wrongly diliberately remove the key from the lockset.